No abstract

The proteins of epididymal luminal fluid and of spermatozoa recovered from different regions of the rat epididymis were examined by polyacrylamide gel electrophoresis under non-denaturing and denaturing conditions. Albumin (A) and four major pre-albumin bands (B-E) were observed in epididymal fluid from the cauda on non-denaturing gels. By comparing the migration of these bands with that of standard globular proteins on denaturing gels, the molecular weight of Bands B and C was estimated to be 16 000, Band D was 30 000 and Band E was 32 000. Bands D and E were apparently glycoproteins since they stained with periodic acid-Schiff's reagent and were bound by an affinity column of Concanavalin A. The pre-albumin proteins (B-E) were of epididymal origin since they (a) were not detected in blood serum, (b) were not detected in testicular extracts and (c) were still found after ligation of the efferent ducts. From the incorporation of radioactive methionine, Bands B and C were shown to be synthesized in the initial segment and caput. The regional distribution of luminal proteins indicated that protein D was added in the caput and cauda and protein E in the cauda. This regional origin of luminal proteins was confirmed by the altered protein profiles consequent upon the reduced fluid flow through the epididymis brought about by ligation of the efferent ducts. The androgen-dependence of epididymal protein synthesis was also investigated using radioactive methionine. Castration had little effect on total protein synthesis but resulted in the specific reduction of the synthesis of proteins B and C. Several changes were observed in the relative amounts of specific proteins extracted from spermatozoa from different regions of the epididymis and several of these proteins had molecular weights identical with those in luminal fluid. However, there was no evidence for any substantial binding to spermatozoa of the pre-albumin proteins (B-E) of luminal fluid.

No abstract

1. Two basic proteins were purified from secretions of rat seminal vesicles by using Sephadex G-200 chromatography and polyacrylamide-gel electrophoresis under denaturing conditions. 2. It is not certain that these two proteins are distinct species and not subunits of a larger protein, but their properties are similar. Highly basic (pI = 9.7), they migrate to the cathode at high pH and their amino acid composition shows them to be rich in basic residues and serine. Threonine and hydrophobic residues are few. Both proteins are glycoproteins and have mol.wts. of 17000 and 18500. 3. Together these two proteins account for 25-30% of the protein synthesized by the vesicles, but they are absent from other tissues. 4. Changes in androgen status of the animal markedly affect these proteins. After castration, a progressive decrease in the basic proteins is observed and the synthesis of the two proteins as measured by [35S]methionine incorporation in vitro is is decreased. Testosterone administration in vivo rapidly restores their rates of synthesis. 5. These effects on specific protein synthesis are also observed for total cellular protein, and it is suggested that testosterone acts generally on the total protein-synthetic capacity of the cell and not specifically on individual proteins. Proliferative responses in the secretory epithelium may also be involved. 6. The extreme steroid specificity of the induction process suggests that the synthesis of these basic proteins is mediated by the androgen-receptor system. 7. The biological function of these proteins is not clear, but they do not appear to be involved in the formation of the copulatory plug.

In a previous report [Higgins et al. (1976) Biochem. J.158, 271-282] we described the effects of alterations in androgen status on the synthesis of two basic secretory proteins of the rat seminal vesicle. In the present paper we examine the effects of testosterone on the activity of mRNA in the seminal vesicle. Total cellular poly(A)-rich RNA was isolated and translated in a cell-free system prepared from wheat germ. Translation products were separated on denaturing polyacrylamide gels and the protein bands corresponding to the two basic secretory proteins were identified immunologically. Incorporation of radioactive methionine into these bands was taken as a measure of the individual mRNA activities. Total mRNA activity was estimated by radioactivity in total acid-precipitable material. The results show that 1 to 2 weeks after castration the activities of mRNA molecules for the basic secretory proteins were decreased 10-20-fold on a tissue basis. Testosterone given in vivo rapidly and substantially restores mRNA activity to normal. Since these changes correlate closely with variations in the rates of synthesis of the secretory proteins in whole cells it suggests that androgenic steroids control protein synthesis chiefly via mRNA availability. In this respect their action resembles those of other steroid hormones acting in other systems. However, these effects of testosterone on the mRNA molecules for the major secretory proteins could not be distinguished from those on total mRNA. Thus the proportion of the total mRNA population accounted for by the two specific mRNA molecules showed less than a 2-fold variation with androgen status. Similarly the two secretory proteins always accounted for 25-33% of general protein synthesis. This is in sharp contrast with the markedly differential effects of other steroid hormones controlling synthesis of major proteins in other well-studied systems. We interpret our results as indicating that testosterone regulates the mRNA population of the seminal vesicle as a whole.

No abstract

Under the influence of testosterone, rat seminal vesicles synthesise large amounts of a tissue specific protein, S. Recombinant X clones have been isolated containing overlapping sequences covering a 27.5 kilo base region of the rat genome within which the gene for protein S is located. Recombinant plasmids bearing cDNA sequences for protein S were constructed in pBR328. One (pcS2) contains a 690 nucleotide insert and is probably full length. Detailed restriction maps of the S-gene are presented and the structure was confirmed by analysis of R-loops and heteroduplexes. The S-gene covers a 2 kbp region of the genome and consists of a 5' intron (490 bp) separating a leading exon (120 bp) containing the 5' untranslated region from a central exon (310 bp) containing most of the coding sequence and part of the 3' untranslated region.

The mouse prostate is an attractive model for studying the relationship between epithelial-mesenchymal interactions and the mechanism of androgen action because of the volume of information on tissue interactions in the development of the prostate of this species and the existence of a mutant mouse lacking functional androgen receptors (Tfm mouse). In this paper the major proteins of the mouse dorsolateral prostate (DLP) have been described, and antibodies to these proteins have been characterized. The two most abundant secreted proteins were of 110,000-115,000 (Mj1) and 55,000-62,000 (Mj2) mol wt. They were glycosylated, androgen dependent, and appeared to exist in an oligomeric complex. Antibodies raised against mouse DLP secretion reacted mainly with Mj1, Mj2, and a minor protein of 140,000 mol wt (Mn1). The antibodies were of a high titer and recognized these three mouse DLP proteins by Western blotting, immunoprecipitation, and immunocytochemical techniques. Mj1 and Mj2 were antigenically similar to proteins in the mouse coagulating gland and in the rat DLP, but were not found in other organs. Immunocytochemical staining of the DLP from intact mice revealed many ducts that were lined by a tall columnar epithelium whose cells stained intensely. However, ducts that were distended with luminal secretion had a low columnar epithelium that rarely showed intracellular staining. These marker proteins and the antibodies to them will be useful for detecting androgen-dependent functional activity in tissue recombinant studies with a variety of experimental tissues.